Instrumentation and computer capabilities that measure, record and duplicate preconscious jaw movements have been developed. This Case Gnathic Replicator System provides a basis for objective study and evaluation of occlusion. In this research, the influence of forces applied by class II elastics and by chin cups will be studied on subjects in orthodontic treatment. Occlusion related problems of tooth loss, mobility, temporomandibular joint dysfunction, muscle pathology and alterations of occlusions will also be studied.